Can't install Sims 3 - detailed information on error messageS

Hi, I bought the Sims 3 starter pack + pets expansion yesterday, installed the game through Origin (that I downloaded when I bought the Sims 3, so it can't be more up to date thant that, now when I use the Sims 3 launcher, I get prompted to download most recent patch. When I accept to download it, it usually crashes at 99.99% or I get the error code -5011 : 0x8000ffff. So i tried uninstalling the game following the steps in the Master Help thread, reinstalled, and I still get the same error message. When I decide to ignore the patch and just skip direclty to play, the game crashes (Message is: the Sims 3 stoped working, Windows will close this program). At some point it seems the patch had went correclty and was complete, then I got the following: Sims 3 update can't continue as associated programs are executed, please stop these applications before trying to update. Thing is, the window following the patch download progress had just closed by itself after being completed so there was no updates that was running when I got this message. Now, I am getting pretty close of the time limit to get my refund (well, half of it anyways) and I am not sure what to do at that point...

keep collecting error messages (that would be some kind of achievement) and hoping that this can somehow be fixed, or just get my refund and forget about playing this game. Did anyone get all those error message combined and actually found a way to resolve it?